In a pressure relief system, a substantial pressure reduction may be experienced by the discharge fluid from a pressure relief valve when the fluid is vented from the system. As a result, the temperature of this discharge fluid may be lowered below the point at which various components of the discharge fluid may form into solids. If the solids accumulate to form a blockage in the discharge piping of the system, the blockage can increase the back pressure of the discharge fluid being exhausted from the valve and thereby keep the relief valve from functioning properly. To keep the solids from forming, prior systems have used steam or electrical tracings to heat the discharge fluids from the relief valve so that the temperature of the discharge fluid is kept above the temperature at which solids may form. Alternatively, anti-solidifying agents have been used to lower the temperature at which solids can form in the discharge fluid. For example, antifreeze has been injected into the discharge fluid to keep ice from forming. However, with respect to the use of anti-solidifying agents, in pressure relief systems designed for high pressure fluids such as process gases, the mass flow of the gases discharged through the relief valve can require the anti-solidifying agent to be pumped into the stream of discharge gases at flow rates higher than that obtainable using a conventional aspirator.
Examples of lower mass flow pressurized piping systems are air braking systems as are described in U.S. Pat. Nos. 1,171,014, 1,884,092 and 1,220,336. The flow of fluid through the piping in these types of systems is used to draw antifreeze from a reservoir into the flowing fluid stream. These pressurized systems, however, handle only very small mass flows at relatively low pressure conditions in comparison to pressure relief systems.
For high pressure relief systems, some prior arrangements have used solenoid actuated pumping devices to inject the anti-solidifying agent into the discharging gas. In the latter type of system, as with systems utilizing steam or electrical tracings, energy is required from a source outside the pressure relief system itself in order to inject the anti-solidifying agent.